Microelectronic assemblies generally include one or more ICs, such as for example one or more packaged dies (“chips”) or one or more dies. One or more of such ICs may be mounted on a circuit platform, such as a wafer such as in wafer-level-packaging (“WLP”), printed board (“PB”), a printed wiring board (“PWB”), a printed circuit board (“PCB”), a printed wiring assembly (“PWA”), a printed circuit assembly (“PCA”), a package substrate, an interposer, or a chip carrier. Additionally, one IC may be mounted on another IC. An interposer may be an IC, and an interposer may be a passive or an active IC, where the latter includes one or more active devices, such as transistors for example, and the former does not include any active device. Furthermore, an interposer may be formed like a PWB, namely without any circuit elements such as capacitors, resistors, or active devices. Additionally, an interposer includes at least one through-substrate-via.
Thinning of dies may be to address a demand for smaller packages, such as for portable communications devices, memory cards, smart cards, portable computing, or the like. However, with increasing wafer diameters, a thicker wafer has been used in order to withstand semiconductor manufacturing. Such thick wafers for semiconductor manufacturing and contrasting desire for thinner dies has led to whole wafer thinning at the back end of the line, namely after completion of processing on a front side of a wafer. Conventionally, wafer thinning involves mechanical grinding, chemical mechanical polishing (“CMP”), wet etching, and/or dry etching.
A wafer may be attached to a transparent platform or carrier. Such carrier may be transparent with respect to light. For example, a wafer may be glued to a glass carrier with use of a photo-releasable adhesive, and then lapped to a desired thickness for thinning. After lapping, a light is shined through such glass carrier in order to effectively cause such photo-releasable adhesive to release such wafer from such carrier. Unfortunately, often a portion of such photo-releasable adhesive sticks to such wafer in an area or areas of one or more dies. Because such wafer has already been thinned, removal of such photo-releasable adhesive without catastrophic damage to one or more formed dies of such wafer may not be possible.
Another approach to removal of an adhesive between a wafer and a carrier may include forming through holes in the carrier for injection of an acid or other adhesive releasing agent. However, use of a releasing agent may likewise not completely remove an adhesive from a wafer.
Accordingly, it would be desirable and useful to avoid one or more of the above-identified limitations in order to increase die per wafer yield.